The present invention relates generally to electronic control systems for managing the operation of an internal combustion engine and other drive line components, and more specifically to systems for controlling such components so as to protect one or more drive line components from excessive engine inertial forces.
Systems for controlling output torque of an internal combustion engine are known and one such system is described in U.S. Pat. No. 5,738,606 to Bellinger which is assigned to the assignee of the present invention, and the contents of which are incorporated herein by reference. One aspect of the Bellinger system is directed to control strategies for limiting engine output torque to the lowest value of the maximum input torque capacities of any of a number of drive train or drive line components. As a result, engine output torque is limited to the maximum input torque capacity of the weakest of the drivetrain components, thereby protecting all drivetrain components from excessive forces resulting from applied engine output torque.
Under certain vehicle operating conditions, the engine may also possesses substantial engine inertial torque which, if not properly accounted for, may also exceed the maximum input torque capacities of one or more of the drivetrain components. Thus, while systems such as that described in the ""606 Bellinger reference may protect drivetrain components from excessive applied engine torque, no systems are known to exist that employ control strategies for protecting one or more of the drivetrain components from excessive engine inertial torque.
As an example of one vehicle operating condition wherein excessive engine inertial torque may damage drivetrain components, consider a tractor-trailer combination backing up to a loading dock in a low gear. If the vehicle operator errs and runs the back of the trailer into the dock, the wheels (as well as the various drivetrain components such as one or more transmissions, tailshaft, drive axle, clutch, etc.) stop rotating, yet the engine still possesses inertia. These rotational inertial forces possessed by the engine are accordingly transferred from the engine output drive shaft directly to the now locked drivetrain. These inertial forces may be substantial and could exceed the maximum input torque capacities of any one or more of the drivetrain components, thus resulting in excessive wear and/or drivetrain damage.
What is therefore needed is a system for protecting drivetrain components from excessive engine inertial torque. Such a system should ideally be operable to determine conditions wherein engine inertial torque is applied to the drivetrain, and implement a control strategy whereby the one or more drivetrain components are protected under conditions wherein the engine inertial torque may be excessive.
The foregoing shortcomings of the prior art are addressed by the present invention. In accordance with one aspect of the present invention, a system for protecting one or more drive line components from excessive engine inertial forces comprises a drive line including an internal combustion engine coupled by a torque converter to a number of additional drive line components, wherein the torque converter is operable in a lockup mode to couple the engine directly to the number of additional drive line components and otherwise operable in a torque converter mode, means for determining a drive line operating parameter and producing a drive line parameter value corresponding thereto, means for comparing the drive line parameter value with at least one drive line parameter threshold corresponding to a maximum input torque capacity of one of the number of additional drive train components, and means for forcing the torque converter to operate in the torque converter mode if the drive line parameter value is less than the at least one drive line parameter threshold.
In accordance with another aspect of the present invention, a method of protecting one or more of the number of additional drive train components from excessive engine inertial forces in a drive line including an internal combustion engine coupled by a torque converter to a number of additional drive line components, wherein the torque converter is operable in a lockup mode to couple the engine directly to the number of additional drive line components and otherwise operable in a torque converter mode, comprises the steps of determining a first drive line operating parameter, comparing the first drive line operating parameter with at least one drive line parameter threshold, and forcing the torque converter to operate in the torque converter mode if the first drive line operating parameter is less the at least one drive line parameter threshold.
In accordance with yet another aspect of the present invention, a method of protecting one or more of the number of additional drive train components from excessive engine inertial forces in a drive line including an internal combustion engine coupled by a torque converter to a number of additional drive line components, wherein the torque converter is operable in a lockup mode to couple the engine directly to the number of additional drive line components and otherwise operable in a torque converter mode, comprises the steps of determining a first drive line operating parameter, comparing the first drive line operating parameter with at least one drive line parameter threshold, and modifying engine fueling if the torque converter is operating in the torque converter mode and the first drive line operating parameter is beyond the at least one drive line parameter threshold to bring the first drive line operating parameter within the at least one drive line parameter threshold.
One object of the present invention is to provide a system for protecting drive line components from excessive engine inertial forces.
Another object of the present invention is to provide such a system wherein the drive line includes a torque converter disposed between an internal combustion engine and a number of downstream drive line components.
Yet another object of the present invention is to provide such a system wherein the torque converter is forced into a torque converter mode of operation, and/or to modify engine fueling if in torque converter mode, whenever drive line acceleration exceeds an acceleration threshold corresponding to a maximum acceleration threshold of one of the downstream drive line components.
Still another object of the present invention is to provide such a system wherein the torque converter is forced into a torque converter mode of operation, and/or to modify engine fueling if in torque converter mode, whenever an estimated engine output torque exceeds a torque threshold corresponding to a maximum torque capacity threshold of one of the downstream drive line components.
These and other objects of the present invention will become more apparent from the following description of the preferred embodiments.